Field
Packaging for microelectronic devices.
Description of Related Art
Microelectromechanical systems (MEMS) devices are a micro or nano device that integrates mechanical and electrical elements on a common substrate typically using microfabrication technology. The mechanical elements are fabricated using lithographic processes on a substrate, such as a silicon substrate, to selectively pattern the devices according to known techniques. Additional layers are often added to the substrates and then micromachined until the MEMS device is in a design configuration. MEMS devices include actuators, sensors, switches, accelerometers, modulators and optical devices (MEMS).
Because a MEMS device typically involves a fabrication of mechanical elements with electrical elements on the same device, such as a silicon die, the real estate available for location and number of devices is limited to the size of the die.
Microelectronic devices, including MEMS devices, are typically contained in a package that allows a connection to another device, such as a printed circuit board. Microelectronic packaging technology, including methods to mechanically and electrically attach a silicon die (e.g., a microprocessor) to a substrate or other carrier continues to be refined and improved. Bumpless Build-Up Layer (BBUL) technology is one approach to a packaging architecture. Among its advantages, BBUL eliminates the need for assembly, eliminates prior solder ball interconnections (e.g., flip-chip interconnections), reduces stress on low-k interlayer dielectric of dies due to die-to-substrate coefficient of thermal expansion (CTE mismatch), and reduces package inductance through elimination of core and flip-chip interconnect for improved input/output (I/O) and power delivery performance.